Windows 2003 Server users can use either their user principal name or their user logon name
User Principal Name
A user principal name is made up of two parts. One part uniquely identifies the user object in AD and the second part identifies the domain where the user belongs to.
The two parts of the user principal name are seperated by using the (@) character. This is enough for Windows Server 2003 to identify which part of the name is the user object name and which is the domain name. The first part is the user id and the second part is known as UPN suffix.
An example of user principal name is as shown below:
User Logon Name (Down-level logon name)
User logon name (Down-level logon name) are used by clients logging on to a Windows Server 2003 network from previous Microsoft operating systems, such as Windows 9x or Microsoft Windows NT 4.
Logging on to a Windows Server 2003 domain using their user logon name (Down-level logon name) means that users must provide two distinct pieces of information. The users must provide their username and also their domain name.
The structure of User Logon name (Down-level logon name)is like DOMAIN\UserName.
An example of User Logon Name (Down-level logon name) is as shown below: